Duplex pump



May 10, 1932. H. PETERS 1,357,364

DUPLEX PUMP Filed Apfil 23, 1930 9W ,WAQ

Patented May 10, 1932 UNITED STATES PATENT OFFICE HANS PETERS, F BERLIN, GERMANY, ASSIGNOR '10 KNOBR-BBEMSE AKTIENGESELL- SCHLAFT, .OF LICHTENIBEBG, BERLIN, GERMANY, A. CORPORATION OF GERHANY DUPLEX rm Application filed April 28, 1980,'Seria1 170. 446,681, and in Germany April 28, 1929.

This invention relates to duplex pumps of the kind in which the plungers or pistons in the two cylinders are in staggered arrangement so that one plunger is about midway in its operative stroke when the other plunger begins its operative stroke. It has been found that an undesirable increase of pressure takes place in the pressure pipe when the second plungerybegins its stroke, especially in steam pumps where the exertion of force is at stroke and then declines according to a curve, and thus the force exerted by the first plunger is reduced at the middle of its stroke when 15. the second plunger comes into operation with its full initial energy; but even in duplex pumps where the driving force is constant throughout the stroke, the same efi'ect occurs when the second plunger comes into. operation. The considerably greater pressure which is suddenly exerted on the liquid in the pressure pipe reacts upon the first plunger, which is about the middle of its stroke, so that the first plunger is momentarily brought to a standstill. Consequently the differential position of the two pump plungers in relation to each other is at this moment disarranged, whereby the object for which this diflerential position is designed, namely, the delivery of a flow of liquid under uniform pressure, is prejudicially affected. The object of the invention is to avoid this difiiculty. According to theinven-tion a compensating device is provided whereby the increase in pressure exerted on the liquid by the second plunger comng into operation is converted into speed of flow. This device. may be a nozzle in the pressure pipe, to which nozzle the currents of liquid arrivin under pressure from the two pump cylin ers are guided separately and combine within the diffuser of the said nozzle. This nozzle is connected by a suitable union with the water space of each cylinder and its diffuser opens into the pressure pipe, which may lead to a boiler or preheater. e

In order that the said invention may be clearlyunderstood and readily carriedinto effect, the same will now be further described with reference to the accompanying the maximum value at the beginning of the liquids alternately rom each of the pump drawing representing in elevation a duplex pump and in section a compensating device exemplifying the practical application of the invention. I

The unions for connection with the pump cylinders A B -are indicated at a and 6 respectively, and 0 indicates the difiuser which passes into the pressure pipe. It will be seen that a suddent increase in the pressure of the current arriving through either of the connections a, b is unable to act in a manner retarding movement upon the other current of liquid or upon the plunger impelling the same, but on the contrary, owing to the conversion of the pressure into energy of flow, causes a reduction in the resistance encountered by that current of liquid which is impelled by the plunger which is in the middle of its stroke. In the diffuser the energy of flow is again converted into pressure energy.

What I claim and desire to secure by Letters Patent of the United States is 1. In a duplex pump for discharging liquids to a pressure pipe alternately from each of the pump outlets, a nozzle in said pressure pipe having tapered'passages each leading from one of the said outlets and converging into a constricted neck in the pressure pipe, whereby the increase of pressure exerted on the liquid already in the nozzle at the beginnig of each discharge stroke of the pump is converted into speed of flow.

2. In a duplex ump for discharging outlets to a common pressure pipe, a' diffuser located at the junction of said pipe with the connections from said outlets, said difli'user comprising a constricted neck and co-axial annular passages converging towards said neck, each of said passages being separately in communication with one of said connections, whereby the reactionof one pump plunger at the beginning of its stroke upon the other pump plunger which is simultaneously at the middle of its stroke is avoided.

3. In a duplex pump for discharging liquids alternately from each of the pump outlets to a common pressure pipe, 9. compensating device located at the junction of said pipe with the connections from said outend of said difl'user.

HANS PETERS. 

